Method of making miniature plug-in fuses of different fuse ratings

Abstract

A method is disclosed for making a plug-in fuse assembly like that disclosed and claimed in U.S. Pat. No. 3,909,767, granted Sept. 30, 1975 for Miniature Plug-In Fuse and having different desired fuse ratings. The method comprises the steps of providing a blank of fuse metal which is initially provided throughout its length with a continuous central portion of reduced thickness having a fixed thickness dimension for making fuses of a variety of fuse ratings, and blanking the blank of fuse metal to contain a pair of laterally spaced coplanar terminal forming blade portions which are interconnected by a transverse web of reduced thickness having a fixed thickness dimension, coplanar current carrying extensions thereof and an interconnecting fuse-forming link portion of reduced thickness having a fixed thickness dimension located in a coplanar platelike body of a plug-in fuse element. The interconnecting fuse-forming link portion of fixed reduced thickness dimension, provided by the blanking of the blank of fuse metal, is arranged in a desired location and is provided with a desired configuration, including width and length dimensions, to provide the desired fuse rating. The method also includes inserting over said blanked blank a synthetic plastic housing by way of an opening at the inwardly facing side thereof with the current carrying extensions of the blank and the interconnecting fuse-forming link portion of fixed reduced thickness dimension within the housing and with the pair of terminal blade portions of the blank, which are interconnected by the transverse web of fixed reduced thickness dimension, extending outwardly from the housing element through the opening therein, securing said blank in the synthetic plastic housing, and blanking the exposed transverse web of fixed reduced thickness dimension interconnecting the terminal blade portions to complete the formation of the coplanar plate-like body having a pair of aterally spaced coplanar terminal portions and of the plug-in fuse assembly.

We claim: 
     
       1. A method of making plug-in fuse elements having different desired fuse ratings and each comprising a plug-in element including a pair of spaced confronting generally parallel terminal forming blade portions to be received by pressure clip terminals or the like, a pair of confronting current carrying extensions projecting longitudinally from the inner ends of the pair of terminal forming blade portions and a fuse-forming link portion interconnecting the current carrying extensions, said method comprising the steps of providing substantially identical blank portions of fuse metal for forming fuse elements of different fuse ratings which blank portions are initially provided within the longitudinal margins thereof with longitudinally extending portions of substantially identical reduced thickness and substantially identical width for fuse elements of different fuse ratings to be made therefrom, blanking said portions of reduced thickness of each blank portion to leave on opposite sides thereof a pair of spaced confronting general parallel terminal forming blade portions to be received by pressure clip terminals of the like and confronting current carrying extensions projecting longitudinally from the inner end portions of each pair of terminal forming blade portions, the fuse elements of different ratings being obtained by blanking said longitudinally extending portions of reduced thickness to provide fuse-forming links of substantially different locations between the confronting portions of said current carrying extensions where the heat dissipation characteristics thereof are substantially different. 
     
     
       2. The method of claim 1 wherein said blanking step forms in said blank portions of different ratings fuse-forming links of different configurations which include a configuration which is relatively straight and a configuration which is undulating. 
     
     
       3. The method of making plug-in fuse elements having different desired fuse ratings and each comprising a plug-in element including a pair of spaced confronting generally parallel terminal forming blade portions to be received by pressure clip terminals or the like, a pair of confronting current carrying extensions projecting longitudinally from the inner ends of the pair of terminal forming blade portions and a fuse-forming link portion interconnecting the current carrying extensions, said method comprising the steps of providing substantially identical blank portions of fuse metal for forming fuse elements of different fuse ratings which blank portions are initially provided within the longitudinal margins thereof with longitudinally extending portions of substantially identical reduced thickness and substantially identical width for fuse elements of different fuse ratings to be made therefrom, blanking said portions of reduced thickness of each blank portion to leave on opposite sides thereof a pair of spaced confronting general parallel terminal forming blade portions to be received by pressure clip terminals or the like and confronting current carrying extensions projecting longitudinally from the inner end portions of each pair of terminal forming blade portions, the fuse elements of different ratings being obtained by blanking said longitudinally extending portions of reduced thickness to provide fuse-forming links of substantially different configurations between the confronting portions of said current carrying extensions. 
     
     
       4. The method of claim 3 wherein said blanking step forms fuse-forming links in the fuse elements of different ratings which have a configuration which is relatively straight and a configuration which is undulating. 
     
     
       5. The method of claim 3 wherein said blanking step forms fuse-forming links in the fuse elements of different ratings which include a relatively U-shaped configuration and a repeatedly undulating configuration. 
     
     
       6. The method of claim 3 wherein said longitudinally extending portions of reduced thickness formed in said blank portions are continuous to extend the full length of said blank portion. 
     
     
       7. The method as defined in claim 3 wherein said blanking step for making fuse elements of different ratings in said identical portions of reduced thickness forms said fuse-forming link portions with substantially different width dimensions. 
     
     
       8. The method as defined in claim 3 wherein said blanking step for making fuse elements of different ratings forms fuse-forming link portions with substantially different lengths. 
     
     
       9. The method as defined in claim 3 wherein said blanking step for making fuse elements of different ratings forms fuse-forming link portions with substantially different width and length dimensions. 
     
     
       10. The method as defined in claim 3 wherein said blank portions of reduced thickness are continuous over the length of the blank portions and are reduced by a step including decreasing the thickness from one side only of the blank. 
     
     
       11. The method of claim 3 wherein said fuse-forming link portions of the fuse elements are too thin to maintain the integrity thereof, said blanking operation leaving a rigid web between each pair of terminal forming blade portions thereof, and the method includes the steps of securing between said current carrying extensions insulating means which rigidly interconnects the same, at least said pair of terminal blade portions of the blank and said rigid web being outside of the insulating means, and blanking the exposed rigid web of fuse metal interconnecting the terminal blade portions. 
     
     
       12. The method as defined in claim 3 including printing the blank in desired selected colors at the current carrying extensions of the plug-in unit for color coding the same in accordance with the desired fuse ratings. 
     
     
       13. The method of making plug-in fuse assemblies having different desired fuse ratings and each comprising a plug-in element including a plate-like body of fuse metal having a pair of spaced terminal forming blade portions to be received by pressure clip terminals or the like, current carrying extensions at the inner ends of said pairs of terminal forming blade portions and fuse-forming link portions of reduced thickness interconnecting the current carrying extensions, said method comprising the steps of providing strips of fuse metal for forming fuse elements of different fuse ratings which strips are initially longitudinally provided within the longitudinal margins and throughout the lengths thereof with continuous portions of reduced thickness, sequentially advancing the continuous strips of fuse metal, blanking said strip portion of reduced thickness to leave on opposite sides thereof at longitudinally spaced intervals in said strip spaced longitudinally extending interconnected pairs of terminal forming blade portions, and current carrying extensions interconnected by fuse-forming link portions of reduced thickness, the fuse elements of different ratings being obtained by forming said fuse-forming link portions of different configurations and/or locations along the confronting margins of said pairs of current carrying extensions, and severing completed plug-in elements from the end of each strip. 
     
     
       14. The method of making plug-in fuse assemblies having different desired fuse ratings and each comprising a plug-in element including a plate-like body having a pair of spaced terminal forming blade portions to be received by pressure clip terminals or the like, current carrying extensions at the inner ends of said terminal forming blade portions and fuse-forming link portions interconnecting the current carrying extensions, and rigid insulating means interconnecting said current carrying extensions and with the pair of terminal forming blade portions thereof extending outwardly from said insulating means, said method comprising the steps of providing strips of fuse metal for forming fuse elements of different fuse ratings which strips are initially longitudinally provided throughout their lengths with continuous central portions of substantially identical reduced thickness and substantially identical width for fuse elements of different fuse ratings to be made therefrom, sequentially advancing the strips of fuse metal, blanking said strips of fuse metal to provide at spaced intervals in said strips longitudinally interconnected blanks containing pairs of laterally spaced terminal forming blade portions formed outside of said reduced thickness portions interconnected by rigid webs formed at least in part in said reduced thickness portions, current carrying extensions at the ends of said pairs of terminal forming blade portions formed externally of said portions of reduced thickness and fuse-forming link portions formed in said portions of reduced thickness, said interconnecting fuse-forming link portions of reduced thickness for the fuse elements of different ratings being obtained by blanking said portions of reduced thickness in said strips of fuse metal which form the differently rated fuse elements so the fuse-forming link portions have substantially different locations and/or configurations, severing the end blanks from the sequentially advanced strips of fuse metal, and anchoring to the current carrying extensions of each end blank a rigid insulating means with the pair of terminal blade portions of the end blank and the rigid web outside of the insulating means, and blanking the rigid webs of each end blank.